The authors have developed a new ultra-high frequency surface acoustic wave (UHF SAW) filter for satellite broadcast receivers. The features are a high center frequency which suppresses image interference, sufficiently flat group delay for linear FM detection, and no necessity to adjust for tuning. The influence of electrode resistance on insertion loss and the triple transit echo caused by surface wave reflection have been analyzed in Smith's (1972) extended equivalent circuit model. This electrode resistance is effectively applied here as an independent design parameter of radiation and load conductance. In consequence, interdigital transducers with wide apertures stretched over the nonoverlapped electrodes have been applied to suppress undesired surface wave diffraction and reflection effects without any increase of insertion loss. These transducers thus eliminate the conventional tuning coils.
ASJC Scopus subject areas
- Media Technology
- Electrical and Electronic Engineering